EASA SIB CASA-2026-03 — Localizer Signal Deviation Disturbances

Summary

Transport Canada Civil Aviation Safety Alert CASA 2026-03 addresses unexpected localizer signal disturbances affecting Airbus Canada Limited Partnership (ACLP) aeroplanes models BD-500-1A10 and BD-500-1A11. The alert raises awareness of these signal deviations during Instrument Landing System approaches, which may cause flight path deviations or autopilot lateral commands. It provides recommendations to mitigate these issues and improve operational safety.

What Changed

This safety alert introduces awareness of localizer signal disturbances linked to improper radome rigging and electrical bonding issues. ACLP has issued a Service Bulletin BD500-538013 to modify the radome assembly and frame to improve conductivity. Additionally, operational procedures have been recommended through Flight Operations Transmission A220-FOT-34-50-001 to manage the disturbances during flight.

Why It Matters

Localizer signal disturbances can degrade approach capability and cause unexpected autopilot lateral commands, potentially requiring manual intervention by flight crews. For operators and maintenance personnel, addressing these issues is critical to maintaining safe and reliable instrument approaches. Compliance with the recommended modifications and procedures helps prevent deviations from normal flight paths and enhances overall flight safety.

What To Do

Owners, operators, and maintainers of ACLP BD-500-1A10 and BD-500-1A11 aeroplanes should incorporate the modifications described in Service Bulletin BD500-538013 Issue 001 dated 30 October 2025 or later revisions. If modifications are not yet incorporated, flight crews must be trained to apply the operational procedures in Flight Operations Transmission A220-FOT-34-50-001 Revision E dated 4 November 2025 or later. Additionally, all occurrences of localizer signal disturbances must be reported to Transport Canada via Service Difficulty Reports as per Canadian Aviation Regulations.